UPSC Civil Services (Mains)
Chemistry optional
- 2 papers
- 250 marks each
- 3 h per paper
- 5 of 8 questions, Q1 and Q5 compulsory
Paper II covers organic chemistry and spectroscopy.
All topics
Paper II, organic chemistry and spectroscopy
Photochemistry: every question, 2021 to 2025
16 parts worth 130 marks have been set on this unit in UPSC CSE Chemistry Paper II from 2021 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.
Syllabus
Photochemical reactions of simple organic compounds, excited and ground states, singlet and triplet states, Norrish Type I and Type II reactions.
Notes: Organic photochemistry: Norrish reactions (full notes) · short notes
2025
- Q5(c) 290 nm or 450 nm for a reaction through T₁?10 marks Answered
- Q6(c)(i) Benzene to fulvene by light5 marks Answered
- Q6(c)(ii) Quantum yield of photobromination5 marks Answered
- Q6(c)(iii) Photolysis of 4,5-dimethylhexan-2-one5 marks Answered
- Q6(c)(iv) A, B and C from the mixed ketones5 marks Answered
2024
- Q5(c) α-Keto esters irradiated in alcohols10 marks Answered
- Q6(b) Photochemistry of a β-hydroxy bicyclic ketone15 marks Answered
2023
- Q5(e) Photolysis of acetone: vapour phase and room temperature10 marks Answered
- Q7(b)(i) Vapour-phase photolysis of cyclopentanone10 marks Question only
- Q7(b)(ii) Direct and benzophenone-sensitised photolysis of 1,3-butadiene5 marks Question only
2022
- Q5(b) Photolysis of 2-methylcyclohexanone in solution10 marks Answered
- Q6(a)(i) Photolysis of a mixture of valerophenone and 5,5-dideuteriohexan-2-one5 marks Answered
- Q6(a)(ii) Photolysis of 4,5-dimethylheptan-2-one10 marks Answered
2021
- Q5(d) Ease of Norrish type II hydrogen abstraction in two groups of ketones10 marks Answered
- Q6(c) I Photolysis of 2-cyclopropylcyclohexanone5 marks Question only
- Q6(c) II Photolysis of 1,1,3-triphenylpropan-2-one10 marks Question only
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UPSC Civil Services (Main) Chemistry Paper II: Model Answers 2021 to 2025
- All eight questions of each paper, with the question printed above its answer
- Mechanisms drawn out and labelled on the scheme
- Topic-wise weightage and a topic-wise index